1. Field of the Invention
The invention relates to a shutter mechanism for a photographic lens. More particularly, the invention relates to an electromagnetic means for remotely causing the shutter to open and close. The invention applies in particular to the art of clustering a group of similar lenses for the purpose of providing sequential photographic views on one sheet of film of images presented upon an oscillascope screen.
The invention makes possible close packing of lenses for instruments used in the medical field. In particular, a group of closely packed lens is very useful for obtaining multiple views of nuclear medicine studies, ultra-sound studies, computed axial topography scans, X-ray fluoroscopy examinations, and other examinations of the human body in which multiple images are produced. The overall instrument containing the cluster of lenses is called in the art, a multiformat image camera.
The invention has an application in the medical field where it is deslrable to place several images from an oscilloscope screen or a television picture tube on a single sheet of film. The images appear sequentially on the oscilloscope tube, and are placed side by side on the sheet of film. Each lens in the cluster focuses one image of the screen onto the film at a position which corresponds to that lens.
The lens cluster makes it possible to place a number of images at particular positions on the film. The electromagnetic-shutter mechanism makes it possible to cluster large aperture lenses in a practical size cluster.
2. Prior Art
Heretofore it has been difficult to build a cluster of lenses with electrically operated shutters, the problem being where to locate the shutter operating mechanism.
An unsatisfactory solution which has been employed in the past has been to attach a solenoid to the outside of the lens body. When the solenoid is energized it pulls a soft iron core which is movably inserted into the solenoid. The core moves into the solenoid under the influence of electromagnetism, thereby pulling a lever which causes the shutter to open. A solenoid is unsatisfactory for several reasons, a principal one being that translational motion of the soft iron core must be converted into other motion in order to open the shutter. The conversion of linear motion requires a crank, pin joints, and much hardware which is subject to wear and misadjustment.
An even less satisfactory method of providing multiple views of an oscilloscope screen on one photographic film is to use one movable lens, rather than a cluster, and to move the lens to a different position for each view. Such systems tend to be very complex in design and expensive to manufacture and maintain.
An additional problem in the art of placing multiple views of an oscilloscope screen on a single photographic film is the problem of using lenses of large aperture. It is advantageous to utilize such large aperture lenses in order to minimize the time required for exposure of the photographic film. Shutters available in the prior art for such lenses are large and bulky. Large and bulky shutters occupy much space. Thus, in mounting such lenses in a cluster to provide multiple views, it is not possible to obtain a favorable ratio of area of lens glass to total area of the cluster. The shutters occupy much area and thereby reduce the amount of glass which the cluster can have. With the area of glass so restricted, large aperture lenses cannot be mounted within a cluster of practical size.